(a) Technical Field
The present disclosure relates generally to an apparatus and a method for controlling torque reduction of a hybrid electric vehicle. More particularly, the present disclosure relates to an apparatus and a method for controlling torque reduction of a hybrid electric vehicle that determines an engine torque command and a motor torque command to satisfy a request for driving torque limit by a traction control system (TCS) and a state of charge (SOC) of a battery.
(b) Description of the Related Art
A hybrid vehicle is a vehicle using two or more different types of power sources and is typically a vehicle that is driven by an engine that obtains a driving torque by burning fuel and a motor that obtains a driving torque by battery power. Hybrid electric vehicles can be provided with optimum output torque, depending on how the engine and the motor are operated while the vehicles are driven by the two power sources, that is, the engine and the motor.
Meanwhile, a traction control system (TCS) is a safety system for preventing wheel spin and improving driving stability by controlling the brakes and the engine during takeoff or acceleration. The TCS is typically provided with the hybrid electric vehicle and requests to limit driving torque when the wheel spin occurs during takeoff or acceleration. Particularly, the hybrid electric vehicle is provided with two power sources. i.e., engine and the motor, so the engine and the motor may be utilized when the TCS requests for driving torque limit.
Conventionally, if a request for driving torque limit by the TCS is generated when the TCS requests torque reduction, the hybrid electric vehicle decreases an engine torque at first. Then, if the decreased engine torque cannot satisfy an amount of the request for driving torque limit by the TCS, the hybrid electric vehicle decreases a motor torque to satisfy the amount of the request for driving torque limit by the TCS.
However, in case that the request for driving torque limit by the TCS is satisfied by using the motor torque after the engine torque becomes 0 (i.e., the engine only outputs a torque to compensate an engine friction torque), a state of charge (SOC) of the battery runs out due to continuous use of the motor, so power performance of the motor is deteriorated. Moreover, a demand torque of a driver cannot be satisfied while the TCS continuously operating, so the hybrid electric vehicle cannot start smoothly again.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure, and therefore, it may contain information that does not form the related art that is already known in this country to a person of ordinary skill in the art.